Flutter kick

The flutter kick is a kicking movement used in both swimming and calisthenics.

In swimming strokes such as the front crawl or backstroke, the primary purpose of the flutter kick is not propulsion but keeping the legs up and in the shadow of the upper body and assisting body rotation for arm strokes. The legs are extended straight backwards in line with the body. They are moved up and down, one leg kicking downwards (relative to the front of the swimmer's body) as the other leg moves up. The knees are slightly bent to facilitate the kicking action, but not too much in order to minimise drag created by the thighs as they move out of the shadow of the swimmer's body. Similarly, toes are pointed to minimize drag.